1. Field of the Invention
This invention relates generally to loudspeakers for reproducing recorded sound, and particularly to a high-performance sound imaging system for reproducing and projecting recorded sound in a manner that simulates or duplicates the listener's presence at a recorded or broadcast event.
2. Prior Art
The art relating to loudspeakers and speaker components for reproducing recorded sound is well defined, particularly within the field of reproducing events recorded on phonographic albums, compact discs, laser optical discs, and similar media, as well as projecting broadcast performances of such events.
The term "sound imaging" has been adopted to identify systems for accurately reproducing and projecting recorded sound in a manner that simulates or duplicates the listener's presence at the recorded or broadcast event. The performance characteristics of such systems are most frequently utilized for reproducing or projecting musical performances, with the technical capabilities and aural aesthetic qualities of high-performance systems being challenged by musical performances currently available on recorded media.
Loudspeaker systems usually include one or more drivers that are disposed within one or more enclosures or cabinets. The conventional drivers are commonly referenced as and will usually include at least one bass (woofer), midrange, and high frequency (tweeter). The trend in moderate to expensive loudspeaker systems has been toward one individual unidirectional bass driver placed on or near the floor of a room with two or more paired sets of midrange and high frequency drivers disposed at a higher elevation from the floor and spaced strategically proximate to the perimeter of the room to project sound energy inwardly toward the listener from multiple directions. In such systems, the location of the drivers may be correlated to different channels of the recorded event, so that the listener perceives spatial orientation or movement during the reproduction or projection of the recorded aural performance, particularly when the aural performance is combined with a visual performance such as an optical laserdisc recording.
U.S. Pat. No. to 5,181,247 to Holl discusses various electronic circuits utilized for selecting between channels for acoustic output in different modes, including video broadcasts and projection of recorded performances to obtain a "surround sound" effect. The Holl '247 patent provides a representative example of current developments in the level of commercially available loudspeaker systems for recorded and broadcast performances, and uses the descriptive phrase "sound image enhancing." However, to those skilled in the art the terms "sound imaging" or "sound image enhancement" are intended to convey a more complex and dynamic representation of the performance or event that was recorded or broadcast, involving the position, placement, and orientation of the drivers relative to one another and with reference to the original microphone or pickup position.
The use of reflected sound energy in enclosures for drivers to accomplish radiation of sound energy is known, as is the use of fiberglass enclosures or partitions to selectively differentiate between varying frequency ranges. A representative example discussing both of these principles is U.S. Pat. No. Re. 31,228 to Bose.